Enable setuptools command 'test'

[jayvdb]

Use setuptools on both Python 2 and 3. Convert unit tests to use Python 2 and 3 compatible syntax, but use 2to3 on Python 3.2 which did not have u'..' syntax.

Run travis tests using setup.py test.

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This change is 

[jayvdb]

Built at https://travis-ci.org/jayvdb/demjson/builds/110100074